1. Field of the Invention
The present invention relates to a system and method for optical disc drive adjustment, and in particular to obtain an optimum tilt angle using the persistence of vision effect during a packaging process.
2. Description of the Related Art
An optical pickup head of an optical disc drive, such as a DVD-ROM player, a DVD Player, or a CD-ROM drive, is an important component for data access. A tilt angle between an optical axis of the optical pickup head and an optical disc is defined for disc use. Obtaining a given tilt angle by precise component control, affects yield rates and product cost, requiring a mechanism to adjust the tilt angle with a given range.
FIG. 1 is a schematic diagram of a conventional structure of an optical disc drive. An optical disc drive comprises an optical pickup head 11, which accesses data from a optical disc, an accessing mechanism 12, which moves optical pickup head 11, a rotating mechanism 13, to maintain stable optical disc rotation, and a circuit board 14, which processes signals. Accessing mechanism 12 comprises two leader pins 15, providing primary and secondary movement respectively, which can be represented as a datum plane for optical pickup head 11. Generally, the height of one end of the primary leader pin is fixed, while the other end is adjustable. Conversely, one or both ends of the secondary leader pin are adjustable, and the datum plane is inclined by adjusting the relative height of both leader pins 15. When an optical disc is placed on rotating mechanism 13, the optical disc and the datum plane of both leader pins 15 form a tilt angle and sway generated by incorrect placement and the rotating mechanism 13 itself.
In the first adjustment procedure during the optical drive packaging process, optical drive components are adjusted with tilt angles and sway using an autocollimator at a workstation, comprising a rotary disc a spindle motor, on which an optical disc is placed. A reflector is located under the autocollimator to sense sway and tilt angle of the rotary disc and the datum plane thereof, represented by leader pins, supporting an optical pickup head, and are adjusted until the tilt angle is zero. In the second testing procedure, the jitter value of the optical pickup head is determined by a jitter meter at another workstation, in which a test disc is placed on the rotary disc to read radio frequency (RF) signals from the optical pickup head using the jitter meter, to determine whether jitter values are within a fixed range.
The adjustment procedures described above have several disadvantages, as described in the following. The jitter meter cannot immediately determine the optimum jitter value of the optical pickup head due to interference caused by noise. Additionally, because the jitter meter indicates the measured jitter value with sway it is difficult to determine whether the optimum jitter value has been obtained, and requires several measurements to obtain the optimum bottom jitter value. Further, different types of optical discs have different optical paths, and the datum plane of each must be adjusted before the optical pickup head can access them. Finally, tilt angle, sway and jitter adjustment cannot be performed simultaneously.